What Is the Difference Between Git Merge and Git Rebase?

Git merge and Git rebase are two powerful tools for integrating changes from one branch into another. Both serve the purpose of combining branches, but they do so in very different ways. Understanding when to use each can help you maintain a cleaner project history and streamline your workflow.

What Is Git Merge?

Git merge is the process of integrating changes from one branch into another. When you perform a merge, Git creates a new commit that combines the histories of the two branches, preserving the existing commit history.

How Git Merge Works

When you merge a branch, Git typically performs a three-way merge, creating a new commit that ties together the histories of the two branches. This new commit has two parents: one from the branch being merged and one from the branch you are merging into.

What Is Git Rebase?

Git rebase is an alternative to merging that rewrites commit history. Instead of creating a merge commit, rebase moves or “reapplies” commits from one branch on top of another. This results in a linear history without merge commits.

How Git Rebase Works

When you rebase a branch, Git takes the commits from your current branch and applies them one by one onto the target branch. The result is a sequence of commits that appear as if they were made after the commits on the target branch, creating a cleaner, more linear history.

Key Differences Between Merge and Rebase

Here are the main differences between Git merge and Git rebase:

  • Commit History: Merge preserves the full history of both branches, including the individual commit history and the merge commit. Rebase creates a linear history, eliminating the original branch structure.
  • Merge Commits: Merge creates a merge commit, which can clutter the history with multiple branches. Rebase avoids merge commits, resulting in a cleaner history.
  • Conflict Resolution: Conflicts can arise in both processes. With merge, conflicts are resolved at the time of the merge commit. With rebase, conflicts are resolved during the reapplication of each commit.
  • Use Cases: Merge is often preferred when you want to preserve the context of feature branches. Rebase is ideal for maintaining a clean, linear history, especially in shared branches like main.

When to Use Git Merge

Git merge is appropriate in scenarios where you want to:

  • Preserve the full history of your project, including all branch structures.
  • Maintain the context of a feature branch, such as for record-keeping or debugging.
  • Integrate changes from long-running branches where preserving the commit history is important.

When to Use Git Rebase

Git rebase is ideal in situations where you want to:

  • Create a clean, linear commit history without unnecessary merge commits.
  • Keep the main branch history clean, especially when working with pull requests or continuous integration workflows.
  • Apply small, incremental changes on top of a shared branch like main or develop.

Best Practices

Here are some best practices to consider:

  • Use merge for integrating feature branches into shared branches.
  • Use rebase for keeping a clean history in your personal branches before merging.
  • Avoid rebasing public branches that other developers are using, as it rewrites history and can cause issues.

Conclusion

Both Git merge and Git rebase are valuable tools, each with its own use cases. Understanding the differences between them will help you choose the right strategy for managing your project’s history and collaborating with your team.